Chair back



FIG. 1 is a perspective view of a first embodiment of a chair backaccording to the present invention;

FIG. 2 is an enlarged rear elevational view of FIG. 1 with the lowerportion broken away for convenience of illustration;

FIG. 3 is a cross-sectional view taken along line 3—3 of FIG. 2;

FIG. 4 is a perspective view of a second embodiment of a chair backaccording to the present invention;

FIG. 5 is an enlarged rear elevational view of FIG. 4 with the lowerportion broken away for convenience of illustration; and,

FIG. 6 is a cross-sectional view taken along line 6—6 of FIG. 5.

The broken lines shown in FIGS. 1 and 4 are for environmental purposesonly and form no part of the claimed design.

The ornamental design for a chair back, as shown and described.